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  2. Lifting gas - Wikipedia

    en.wikipedia.org/wiki/Lifting_gas

    Helium is the second lightest gas (0.1786 g/L at STP). For that reason, it is an attractive gas for lifting as well. ... When released into the atmosphere, e.g., when ...

  3. Helium - Wikipedia

    en.wikipedia.org/wiki/Helium

    Helium is the least water-soluble monatomic gas, [96] and one of the least water-soluble of any gas (CF 4, SF 6, and C 4 F 8 have lower mole fraction solubilities: 0.3802, 0.4394, and 0.2372 x 2 /10 −5, respectively, versus helium's 0.70797 x 2 /10 −5), [97] and helium's index of refraction is closer to unity than that of any other gas. [98]

  4. Noble gas - Wikipedia

    en.wikipedia.org/wiki/Noble_gas

    The reason is that there is no primordial helium in the atmosphere; due to the small mass of the atom, helium cannot be retained by the Earth's gravitational field. [71] Helium on Earth comes from the alpha decay of heavy elements such as uranium and thorium found in the Earth's crust, and tends to accumulate in natural gas deposits. [71]

  5. Explainer-What is helium and why is it used in rockets? - AOL

    www.aol.com/news/explainer-helium-why-used...

    Helium is inert - it does not react with other substances or combust - and its atomic number is 2, making it the second lightest element after hydrogen. Rockets need to achieve specific speeds and ...

  6. Exosphere - Wikipedia

    en.wikipedia.org/wiki/Exosphere

    The most common molecules within Earth's exosphere are those of the lightest atmospheric gases. Hydrogen is present throughout the exosphere, with some helium , carbon dioxide , and atomic oxygen near its base.

  7. The world is running out of helium. Here's why doctors are ...

    www.aol.com/news/world-running-helium-heres-why...

    A global helium shortage has doctors worried about one of the natural gas’s most essential, and perhaps unexpected, uses: MRIs.. Strange as it sounds, the lighter-than-air element that gives ...

  8. Heterosphere - Wikipedia

    en.wikipedia.org/wiki/Heterosphere

    The heterosphere of Earth begins at about 100 km altitude and extends to the outer reaches of its atmosphere. [3] It incorporates most of the thermosphere and all of the exosphere. The major constituents of Earth's heterosphere are nitrogen, oxygen, helium, and hydrogen. Nitrogen and oxygen compose the lower portion of the heterosphere.

  9. List of gases - Wikipedia

    en.wikipedia.org/wiki/List_of_gases

    This list is sorted by boiling point of gases in ascending order, but can be sorted on different values. "sub" and "triple" refer to the sublimation point and the triple point, which are given in the case of a substance that sublimes at 1 atm; "dec" refers to decomposition. "~" means approximately.